David K. Chester

Human vulnerability in volcanic environments: the case of Furnas, São Miguel, Azores

Abstract The need to examine the vulnerability of people to natural hazards, in addition to the long-established requirement to study extreme events of nature, is being increasingly recognised within disaster research. Following a discussion of the nature of human vulnerability, we propose a framework for its analysis within the context of volcanic activity and we exemplify our approach by a detailed study of Furnas, a village located at the centre of a volcano with the same name on the island of Sao Miguel in the Azores. The methods used included in-depth interviews with permanent residents (n=50), analysis of census records and an examination of the socio-economic history of the town. The vulnerability of an individual to volcanic hazards involves a complex interaction of elements which, in addition to the usual factors taken into account in programmes of hazard reduction (e.g., the nature of the physical threat, location and economic situation), also comprises his or her social context and a number of physiological and psychological considerations. It is argued, further, that both generally and in the case of Furnas, the root causes of vulnerability lie in the history and development of society. Individual decision making is fundamental but takes place within and cannot be separated from this social context. Vulnerability analysis allows the identification of points where intervention may be successful in reducing the likelihood of suffering in a society. It avoids the problem of peoples unexpected reactions to invention leading to a changing or even increasing level of vulnerability, by studying society rather than just one aspect of volcanic hazard in isolation.

The 1755 Lisbon earthquake

Affecting an area of ca. 800 000 km2 and killing up to 100 000 people, the Lisbon earthquake of 1755 is probably the greatest seismic disaster to have struck western Europe. The shock waves of the earthquake placed a temporary brake on the emerging rationalism of the European Enlightenment and attempts to explain the disaster in terms of human sinfulness coloured many contemporary accounts. Notwithstanding these difficulties, through careful archival research it has proved possible to obtain relatively value-free accounts of most aspects of the earthquake and to use these not only to model the physical characteristics of and damage caused by the earthquake, but also to consider the implications for present day hazard assessment and urban planning. This paper reviews the progress that has been made in: identifying source and faulting mechanisms; the processes involved in the generation and impact of tsunamis; damage caused to different types of building and the use being made of historical earthquakes of different sizes - of which the 1755 event is the largest - in defining future hazard scenarios for Lisbon and other areas of Iberia.

The increasing exposure of cities to the effects of volcanic eruptions: A global survey

Abstract The most dynamic demographic process of the past 250 years has been the movement of people from rural areas to cities. For most of this period urbanisation has been concentrated in economically more developed parts of the world, but during the last 50 years the focus has shifted to economically less developed regions. Urbanisation, particularly in developing countries, has led to increasing global exposure to a variety of natural hazards, not the least of which are risks posed to large cities by volcanoes. In this paper we monitor these demographic changes and detail the various types of volcanic hazard to which cities are exposed. A major eruption affecting a city in a developing country could cause widespread loss of life and regional disruption. Effective response, however, might minimise casualties in a city within a developed nation affected by a major eruption, but the economic impact could have global consequences. We argue that global hazard exposure is often subtle and involves not only the size of a city and the types of volcanic product that may occur, but also the strategic position of the threatened city within the economy of a country and/or region and the fact that volcano-induced tsunami and other consequences of eruptions, such as climatic change, may affect cities far removed from a given eruption site. Mitigation measures informed by both specific prediction (surveillance) and general prediction (hazard mapping) are providing the potential to reduce hazard exposure. The paper concludes with a consideration of ongoing research, in particular the emphasis currently being placed on conflating hazard analysis with studies of place, economy, society and culture.

Volcanic hazard assessment in western Europe

Volcanology has been in the past and in many respects remains a subject dominated by pure research grounded in the earth sciences. Over the past 30 years a paradigm shift has occurred in hazard assessment which has been aided by significant changes in the social theory of natural hazards and the first-hand experience gained in the 1990s by volcanologists working on projects conceived during the International Decade for Natural Disaster Reduction (IDNDR). Today much greater stress is placed on human vulnerability, the potential for marginalisation of disadvantaged individuals and social groups, and the requirement to make applied volcanology sensitive to the characteristics of local demography, economy, culture and politics. During the IDNDR a methodology, broadly similar to environmental impact analysis, has emerged as the preferred method for studying human vulnerability and risk assessment in volcanically active regions. The characteristics of this new methodology are discussed and the progress which has been made in innovating it on the European Union laboratory volcanoes located in western Europe is reviewed. Furnas (Sao Miguel, Azores) and Vesuvius in Italy are used as detailed case studies.

Responding to disasters within the Christian tradition, with reference to volcanic eruptions and earthquakes

Abstract Particularly within Christianity and Judaism, theodicy is defined as any attempt to reconcile notions of a loving and just God with the reality of human suffering. The paper begins with a review of the ways in which the Hebrew and Christian scriptures (i.e. the Old and New Testaments) have interpreted disasters, particularly those caused by earthquakes and volcanic eruptions. Theological analysis of disasters did not end at the close of the biblical era, but has continued throughout Christian history and a number of so called Leibnizian philosophical models of theodicy have been developed. These are critically introduced. In the past few decades there has been a sea‐change in both Christian attitudes towards disasters and in the ways in which losses are viewed by hazard researchers. From the perspective of the latter, an approach that envisions disasters as being primarily caused by extreme physical events has been largely replaced by one in which disasters are studied as social constructs, with a greater emphasis being placed on human vulnerability. Academic scholarship on the Leibnizian philosophical models continues, but greater prominence is now given to viewing disasters as events that represent human sinfulness which is manifested in national and international disparities in wealth, poverty, hazard preparedness and disaster losses. Finally, it is proposed that these new hazard analytical and theological perspectives are synergetic: allowing on the one hand churches, their members as well as their leaders, more fully to engage in disaster relief; whilst, on the other, enabling civil defence planners more effectively to use the often considerable human and financial resources of Christian communities and their charitable agencies

Post-collapse volcanic history of calderas on a composite volcano: an example from Roccamonfina, southern Italy

Roccamonfina, part of the Roman Potassic Volcanic Province, is an example of a composite volcano with a complex history of caldera development. The main caldera truncates a cone constructed predominantly of this caldera may have been associated with one of the ignimbritic eruptions of the Brown Leucitic Tuff (BLT) around 385 000 yr BP. The Campagnola Tuff, the youngest ignimbrite of the BLT, however, drapes the caldera margin and must postdate at least the initial stages of collapse. During the subsequent history of the caldera there were several major explosive eruptions. The largest of these was that of the Galluccio Tuff at about 300 000 yr BP. It is likely that there was further collapse within the main caldera associated with these eruptions. It is of note that despite these subsequent major explosive eruptions later collapse occurred within the confines of the main caldera. Between eruptions caldera lakes developed producing numerous lacustrine beds within the caldera fill. Extensive phases of phreatomagmatic activity generated thick sequences of pyroclastic surge and fall deposits. Activity within the main caldera ended with the growth of a large complex of basaltic trachyandestite lava domes around 150 000 yr BP. Early in the history of Roccamonfina sector collapse on the northern flank of the volcano formed the northern caldera. One of the youngest major events on Roccamonfina occurred at the head of this northern caldera with explosive activity producing the Conca Ignimbrite and associated caldera. There is no evidence that there was any linkage in the plumbing systems that fed eruptions in the main and northern calderas.

MOUNT ETNA VOLCANO: ENVIRONMENTAL IMPACT AND PROBLEMS OF VOLCANIC PREDICTION

Mount Etna, the largest continental volcano in the world, has a substantial environ? mental impact on the local area. Indeed, the Etna region is one of the most prosperous and densely populated parts of Sicily. This derives in large measure from the ample water supply from the porous lavas and the fertile volcanic soils. Nowhere on the slopes of the volcano, however, is free from the risk of damage by eruptive activity. The volcanic hazard, which on Mt Etna is mainly from lava flows, can be considered in two parts, firstly risk to settlements and secondly, potential damage to agricultural land. There is a fairly complete record of the location and nature of the eruptions of Mt Etna over the last 400 years. If it is assumed that the activity in the near future will follow the same pattern as that of the recent past, it is possible to construct a generalpredictive model of the volcanic eruptions of Mt Etna. The prob? lems and limitations encountered in trying to develop such a predictive model are considered in this account.

Monte Vulture Volcano (Basilicata, Italy): an analysis of morphology and volcaniclastic facies

The earliest activity of Monte Vulture, central Italy, included ignimbrites but the bulk of the volcano was built up by plinian airfall deposits. Contemporaneous remobilisation of these deposits formed an apron of lahars around the base of the main cone. The volcano was constructed on a ridge; the valley to the east and tributaries to the north and south became sediment traps for volcaniclastic materials emplaced by fluvial reworking and directly from volcanic activity. To the west the valley was swept clear by active downcutting. Instability of the west flank as a result of this erosion was probably a contributory cause of major gravitational sector collapse on the volcanos flank, terminating the main cone-building phase. The resultant scar is an amphitheatre-shaped hollow called here the Valle dei Grigi. Previous workers have attributed this feature to coalescing calderas formed by engulfment. The last volcanic phase was the production of the Monticchio calderas and associated phreatomagmatic explosions producing airfall and surge deposits. Because most of the activity at Vulture has been repeated plinian eruptions producing similar assemblages of products, detailed stratigraphy of the volcano is difficult to accomplish. To characterise Vulture in terms of its products, various facies are identified and interpreted in relation to volcanic processes, distance from vent and environmental conditions.

Statistical analysis of the frequency of eruptions at Furnas Volcano, São Miguel, Azores

Abstract Furnas Volcano is one of three major volcanic centres on the island of Sao Miguel, Acores. Both Furnas and Fogo have displayed violent explosive activity since the island was first occupied in the early 15th century AD. There is concern that future volcanic activity will not only cause major economic losses, but will also result in widespread mortality, and it is for these reasons that a major programme of hazard assessment has been undertaken on Furnas. The present study is part of this programme and involves both the general statistical modelling of the record of historic eruptions and, more specifically, develops a technique for determining the rate of volcanic eruptions ( λ ), an important parameter in the Poisson probability model.

Holocene alluviation in the Algarve, southern Portugal: The case for an anthropogenic cause

Abstract Finding a causal mechanism to account for observed phases of valley alluviation in the Mediterranean region and southern Europe during the Holocene has been a subject of debate for more than 20 years. Three possible causes have been suggested: regional climatic change, anthropogenic induced erosion and the crossing of intrinsic thresholds within fluvial systems so that deposition, rather than erosion, is favoured. In this paper we report investigations carried out in the Algarve region (southern Portugal), where past research is interpreted as suggesting a climatic cause. Mapping and sedimentological investigations of Holocene sediments within three major valleys in this region are reported, together with the association of these deposits with artifacts, a Roman/Moorish mill and bands of charcoal. Chemical, as well as physical sedimentological interpretation, was carried out on the deposits. We also report the results of a detailed investigation and reconstruction of the land use and settlement history of the area and show that episodes of valley alluviation coincide in time with phases of intensive agriculture and clearance within the catchments of these valleys, whereas episodes of valley erosion coincide with episodes of relative stability. Whilst recognizing that temporal correlations are not necessarily causal, we argue that in this area anthropogenic forcing of phases of Holocene alluviation is the preferred mechanism.